Attachment Radiation Hazard Stu

This document pretains to SES-LIC-20110831-01009 for License on a Satellite Earth Station filing.

IBFS_SESLIC2011083101009_913903

Radiation Hazard Study Exhibit A Analysis of Non-Ionizing Radiation for MorganFranklin (West Chicago, IL), Earth Station System This report analyzes the non-ionizing radiation levels for the earth station system comprised of three antennas; 3.8-meter C-Band (fixed), 2.4-meter Ku-Band (fixed), and a 1.8-meter Ku-Band (fixed). The analysis and calculations performed herein comply with the methods described in the FCC Office of Engineering and Technology (OET) Bulletin #65, Edition 97-01. Radiation safety limits conform to the FCC R&O 96-326. Maximum Permissible Exposure (MPE) limits are specified in these documents. The MPE limits are defined for General Population/Uncontrolled environment (30 minute maximum exposure) and Occupational/Controlled environment (6 minute maximum exposure). These limits are classified by frequency bands as the human absorption rates vary significantly over frequency. This study will focus on the frequency bands that encompass 5,925 MHz through 6,425MHz and 14,000MHz through 14,500MHz, the frequencies of interest to this earth station system. The purpose of this study is to determine power flux densities of the earth stations in the near-field, transition, and far-field regions, as well as the immediate areas on and around the reflectors. These levels will be compared to the MPE limits established by the FCC OET Bulletin #65. MPE Limits General Population/Uncontrolled environment = 1.0 mW/cm². Occupational/Controlled environment = 5.0 mW/cm². Table 1: Formulas & Parameters Used to Calculate Power Flux Densities Parameter Symbol Formula Ant-1 Ant-2 Ant-3 Units Antenna Diameter D Given 3.8 2.4 1.8 m Antenna Surface Area Asurf π D2 / 4 11.34 4.52 2.54 m2 Frequency F Given 6175 14250 14250 MHz Wavelength λ 300 / F 0.04858 0.02105 0.02105 m Transmit Power P Given 28 4 4 W Antenna Gain Ges Given 46.8 49.3 46.0 dBi Antenna Gain Factor G 10Ges/10 47863.0 85113.8 39810.7 n/a Antenna Efficiency η G λ2/( π2D2 .793 .664 .552 n/a 1 of 4

Radiation Hazard Study Exhibit A At the Antenna Surface Power flux density at or around the reflector surface Power at the Reflector Srefl = 4 P / Asurf (1) Ant-1 Ant-2 Ant-3 Units 0.99 0.35 0.63 mW/cm2 On-Axis Near Field Region Calculation Power flux density is considered to be at a maximum throughout the entire length of the defined Near Field Region. This region is contained in a cylindrical volume having the same diameter as the antenna reflector. Extent of the Near Field region Rnf = D2 / (4 λ ) (2) Ant-1 Ant-2 Ant-3 Units 74 68 38 m Near Field Power Density Snf = 16.0 η P / (π D2) (3) Ant-1 Ant-2 Ant-3 Units 7.8 2.3 3.5 W/m2 0.78 0.23 0.35 mW/cm2 On-Axis Transition Region Calculation The Transition region is located between the Near and Far Field regions. The maximum power density in the Transition region will not exceed that calculated in the Near Field region. Safe operating distances are calculated based on the Maximum Permissible Exposure Limits previously listed. Transition region Power Density St = Snf Rnf / R (4) Safe Operating Distance (solve for R) Environment Ant-1 Ant-2 Ant-3 Units Uncontrolled In NF region In NF region In NF region m Controlled In NF region In NF region In NF region m 2 of 4

Radiation Hazard Study Exhibit A On-Axis Far Field Region Calculation The on-axis power density in the Far Field region varies inversely with the square of the distance. Distance to the Far Field region Rff = 0.60 D2 / λ (5) Ant-1 Ant-2 Ant-3 Units 178 164 92 m Far Field region Power Density Sff = G P / (4 π Rff2) (6) Safe Operating Distance (solve for R) Environment Ant-1 Ant-2 Ant-3 Units Uncontrolled In NF region In NF region In NF region m Controlled In NF region In NF region In NF region m Off-Axis Levels at the Far Field Limit and Beyond In the far field region, the power is distributed in a pattern of maxima and minima (sidelobes) as a function of the off-axis angle between the antenna centerline and the point of interest. Off-axis power density can be estimated using the antenna patterns prescribed for the particular antenna. The FCC/ITU developed the following calculation which is commonly used for satellite transmit antennas. Far Field region Power Density Goff = 32 – 25log(Θ) (7) For Θ from 1 to 48 degrees; -10 dBi from 48 to 180 degrees Calculating for 1 degree off axis: Soff = Sff Goff / G (8) Ant-1 Ant-2 Ant-3 Units .0002 .00003 .0001 mW/cm2 3 of 4

Radiation Hazard Study Exhibit A Off-Axis Power Densities in the Near Field and Transitional Regions According to Bulletin 65, for distances at least D meters away from the centerline of the main beam, the power density at that point is at least 20 dB less than the equivalent on- axis power density in the main beam. Power Density off-axis Snf(oa) = Snf / 100 at D off-axis (9) Ant-1 Ant-2 Ant-3 Units .0078 .0023 .0035 mW/cm2 Region Between Feed Horn and Reflector Transmissions from the feed horn are directed to the reflector surfaces and are confined within a conical shape defined by the feed horn. The energy between the feed horn and the reflector is conceded to be in excess of any limits for permissible exposure. These areas are not accessible to the general public. Operators and technicians will receive training specifying that these are high exposure areas. Procedures will be established that will assure that all transmitters are turned off prior to access into these areas. Conclusions Based on the calculations above, it is concluded that the FCC MPE guidelines have been exceeded. The applicant proposes to comply with the MPE limits by one or more of the following methods. The earth stations are confined within chain link fence. The fenced area entry is limited to approved personnel that have received proper training thus creating a controlled environment. Public safety is thereby ensured for the near and far field regions of the Uncontrolled Environment. Occupational exposure will be limited, and the transmitter will be turned off during periods of maintenance, so that the MPE standard of 5.0 mW/cm2 will be met for those regions in close proximity to the main reflectors which could be occupied by operating personnel. 4 of 4


Document Created: 2011-08-26 14:46:28
Document Modified: 2011-08-26 14:46:28
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